Decision

GDA Step 2 of the Rolls-Royce SMR: fundamental assessment public summary

Updated 30 July 2024

Applies to England and Wales

Executive summary

New nuclear power stations are an important part of the government’s plans for generating secure low carbon energy.

As regulators of the nuclear industry, the Environment Agency, Natural Resources Wales and the Office for Nuclear Regulation (ONR) are working together to make sure that any new nuclear power stations built in the UK meet high standards of safety, security, environmental protection and waste management.

The generic design assessment (GDA) process allows the UK’s nuclear regulators to assess new nuclear power station designs at an early stage of the regulatory process and to provide confidence that these new designs can be operated in the UK. Early assessment of the design allows us to identify any potential design issues and ask the reactor design company to address them. This will help to avoid potentially costly and time-consuming changes when the reactor is being built.

Rolls-Royce SMR Limited submitted the Rolls-Royce Small Modular Reactor (Rolls-Royce SMR) design to the UK government for entry into GDA in December 2021. The government decided that Rolls Royce SMR Limited was ready to enter GDA. It asked the regulators (Environment Agency, ONR and Natural Resources Wales) to begin the assessment process which started on 3 April 2022.

Rolls-Royce SMR Limited is the company that is designing the reactor, also known as the Requesting Party (RP) for this GDA.

Rolls-Royce has seven decades of experience of designing and manufacturing nuclear reactors.

The Rolls-Royce SMR is a pressurised water reactor (PWR) which is capable of generating 470 megawatts of electricity. The company says it could power one million homes.

We completed Step 1 of GDA (called ‘initiation’) on the Rolls-Royce SMR design. We have now completed Step 2 of the GDA (called ‘fundamental assessment’) and concluded that we can progress to Step 3 of GDA which is called ‘detailed assessment’.

This document summarises our main report and provides background on the GDA process, consents, our public engagement and next steps.

1. New nuclear power stations – the government’s view

Energy policy, including the use of nuclear power, is a matter for government. Government published an Energy white paper: Powering our Net Zero Future in 2020 that set out the need for nuclear power, among other measures, to help the UK achieve net zero by 2050.

In 2022, the government also published the British Energy Security Strategy. This states an aim that by 2050, up to 24 gigawatts or a quarter of the electricity used in Great Britain will be from nuclear. This ambition was reinforced through the Civil Nuclear Roadmap, published in January 2024, which sets out the government’s vision for the sector and important enabling policies to achieve this.

The Environment Agency has published its own plan EA2025 creating a better place to guide its activities.

The Environment Agency’s 5-year action plan (EA2025) sets out 3 goals:

• a nation resilient to climate change
• healthy air, land and water
• green growth and a sustainable future

Natural Resources Wales has published a corporate plan to 2030 with a vision of nature and people thriving together. This will be achieved through collective action towards:

• nature’s recovery
• resilience to climate change
• minimising pollution

We will continue to work with the government, regulatory partners, industry and others to enable nuclear energy production. And we will make sure that people and the environment are properly protected. Nuclear is a low carbon energy source that could contribute significantly towards net zero goals and implementing the British Energy Security Strategy.

Our processes align with the goals in EA2025 because they help make sure that nuclear power stations are designed and operated in ways which minimise waste, consider sustainability and protect the environment.

2. Regulating nuclear power stations

The Environment Agency and Natural Resources Wales regulate the effects of nuclear sites in England and Wales on people and the environment. They do this by issuing environmental permits which cover:

• preparing the site and constructing the power station
• operating and decommissioning the power station

We also work closely with ONR, which regulates the nuclear safety, conventional health and safety, security and safeguards aspects of nuclear sites.

Our process for assessing and permitting new nuclear power stations can include 2 stages; generic design assessment and environmental permitting.

2.1 Generic design assessment (GDA)

GDA is where we assess the environmental aspects of a power station design that would be relevant to any site. We call this a ‘generic site’. Later, when we assess applications for environmental permits, we use the actual characteristics of the specific site where the developer proposes building the power station. The site-specific characteristics may be different from those of the GDA generic site.

The Environment Agency and ONR developed the assessment process. Natural Resources Wales participates in GDA where a new nuclear power station design is likely to be proposed for construction in Wales.

The GDA of a new design is not a legal requirement. Developers of nuclear power stations may choose to apply to the government to enter GDA to get an early view from regulators on their design. This helps to reduce risks to the developer over the entire project and allows the regulators to ask for changes to the design before construction begins. The government asks the regulators to start a GDA if it decides the nuclear power station design company is ready to enter GDA.

GDA allows us to begin scrutinising the environmental aspects of new nuclear power station designs well in advance of construction starting. It means that we can identify any potential design issues early and ask the reactor design company to address them.

GDA is a flexible process with up to 3 steps. The assessment becomes increasingly more detailed with each step. At the end of each step, we will issue statements and reports about our findings. If the reactor design company still has significant issues to resolve after we have completed our planned assessments, we can (with agreement) add further steps to the process to resolve any remaining issues.

Step 1: Initiation

This is the preparatory part of the design assessment process when we make agreements with the reactor design company and provide advice on the scope and the information it needs to provide for the GDA. As part of this step, we carry out a readiness review and confirm that the reactor design company has put in place the arrangements needed for the GDA process.

Step 2: Fundamental assessment

This is when the first technical assessment takes place. It focuses on the environmental protection features of the design. The regulators will issue a Step 2 statement at the end of the step. A requesting party may wish to stop the GDA at the end of Step 2 or proceed into Step 3. Getting to the end of Step 2 normally takes around 2 years. This is the step we have just completed for the Rolls-Royce SMR design.

Step 3: Detailed assessment

This is a detailed assessment of the environment case. This step is optional and includes a public consultation where we ask for views. We consider all relevant responses before completing our assessments and making our decision. Getting to the end of Step 3 normally takes 4 years. At the end of Step 3, we will issue a Step 3 statement.

At the end of Step 3, we will publish a decision document that sets out our decision about which of the following steps we will take.

Issue a Statement of Design Acceptability (SoDA)

We will issue a SoDA if the design is acceptable. This means we:

• have not found any GDA issues
• consider that the design is capable of being constructed, operated and decommissioned in a way that complies with our regulatory requirements and expectations
• believe that people and the environment will be properly protected

Issue an interim Statement of Design Acceptability (iSoDA)

We will issue an iSoDA if we are broadly content with the environmental protection aspects, but there are still issues to be resolved and the RP has provided credible plans for addressing them. Normally, once it addresses these issues, we will issue a full SoDA.

Not issue a SoDA or iSoDA

We will not issue a SoDA or iSoDA if the design is unsuitable and will not provide the right levels of environmental protection. This could also be because there are GDA Issues but no credible plan to resolve them. We may also not issue either a SoDA or iSoDA if the requesting party did not want to carry out a full GDA.

Our GDA guidance for the reactor design company sets out in detail the process that we follow.

Completed GDAs

We have previously carried out generic design assessment on 4 different reactor designs:

• EDF-Areva’s UK EPR completed in December 2012 and currently under construction at Hinkley Point C in Somerset and proposed for use at Sizewell C in Suffolk
• Westinghouse’s AP1000, completed in March 2017
• Hitachi-GE’s Advanced Boiling Water Reactor (ABWR), completed in December 2017
• General Nuclear System Limited’s UK HPR1000, completed in February 2022

Current GDAs

We are currently assessing the following reactor designs:

• Rolls-Royce SMR Limited’s Small Modular Reactor
• Holtec International’s SMR-300 small modular reactor
• GE Hitachi Nuclear Energy’s BWRX-300 small modular reactor

2.2 Environmental permits

In order to build and operate a new power station at a specific site, a company must apply for environmental permits from the Environment Agency or Natural Resources Wales if the site is in Wales.

These permits cover site investigation and preparation, construction works and associated developments such as workers’ accommodation, operation and decommissioning.

Site preparation and construction works permits include activities such as:

• drilling boreholes
• abstracting groundwater
• discharging treated effluents
• using mobile diesel electricity generators

Operational permits are needed to:

• dispose of and discharge radioactive waste
• operate standby power supply systems using diesel generators
• discharge returned abstracted water (from the cooling water system and fish recovery and returns system) and other liquid trade effluents (including treated sewage effluent) to the sea or inland water body

If we receive permit applications, we will decide whether or not to grant the permits and, if so, what conditions we should apply. When making decisions about site-specific permit applications, we will take account of matters relevant to the specific site as well as the GDA for the design proposed for the site.

We will also carry out a public consultation before deciding whether to grant permits for a specific site. We will make our decision once we have considered the comments we receive in the consultation. We may also receive applications for changes (variations) to the environmental permits and, where appropriate, we will consult on these.

3. The Rolls-Royce SMR

There are currently around 440 nuclear reactors operating around the world. One of the most common types is the pressurised water reactor (PWR), with around 300 PWRs operating.

There are a range of sizes and uses for PWRs, including power generation and marine propulsion.

The Rolls-Royce SMR is a PWR which is capable of generating 470 megawatts of electricity. The company says it could power around one million homes.

The Rolls-Royce SMR is still being designed and is, therefore, not yet in operation. This GDA is the first regulatory assessment of the Rolls-Royce SMR globally.

Rolls-Royce SMR Limited has several shareholders and partners including UKRI Innovate UK, a non-departmental public body sponsored by the Department for Science, Innovation and Technology (DSIT).

Figure 1. An illustration of the reactor

© Rolls-Royce SMR Limited

How does a PWR reactor work?

In the reactor core, some of the uranium atoms that make up the fuel split in a process called nuclear fission. These fission reactions produce energy in a continuous process known as a chain reaction.

The energy created by the fission reactions heats water inside the reactor, which is circulated by pumps in the primary circuit to a steam generator. In the steam generator, the very hot primary circuit water is used to heat water in the separate secondary circuit, producing steam which is fed to a turbine. This makes the turbine spin and drives a generator that produces electricity.

The primary circuit of a PWR is at a very high pressure, giving this type of reactor its name.

There is a third water circuit which is used to cool the condenser of the turbine, converting the steam of the secondary circuit back to water. This is then pumped back around the secondary circuit to flow through the steam generator again.

In UK nuclear power stations, which tend to be in coastal locations, sea water is usually used in the third water circuit, but this can be replaced by water from rivers or estuaries, or water can be cooled using cooling towers.

Other features include:

• a spent (used) fuel storage pond
• spent fuel dry store
• water treatment systems for maintaining the chemistry of the water circuit
• radioactive waste treatment and storage facilities
• back-up systems for providing power in the event of loss of electrical supply from the grid

The Rolls-Royce SMR would be mostly constructed and assembled in factory-built modules. Rolls-Royce SMR Limited is setting up a Module Development Facility within the University of Sheffield’s Advance Manufacturing Research Centre to manufacture and test prototype modules for its small modular reactors (SMRs).

Find out more on the Rolls-Royce SMR GDA website.

4. About Step 1 (initiation) and our decision

We began GDA on the Rolls-Royce SMR in April 2022. We completed Step 1, the initiation stage and published our report on 3 April 2023.

5. About Step 2 (fundamental assessment) and our decision

We began Step 2 on 3 April 2023. We have now completed Step 2, the fundamental assessment stage and published our Step 2 statement and our assessment report. 

The objectives of Step 2 were:

• for the Environment Agency to carry out an assessment to identify any fundamental environmental protection shortfalls in the design
• for the RP to complete the submissions needed for Step 2 (and Step 3, if necessary)
• to confirm if the RP has understood the regulatory approach used in the UK and whether the design can comply with UK regulations and Environment Agency guidance
• to identify the additional work the RP may need to carry out in Step 3 or as part of a future assessment stage

During Step 2, we continued the joint assessment with ONR of the management arrangements used by the RP during GDA to give us confidence in the quality of its submissions.

We also provided feedback to the RP on:

• the structure of the submissions
• the information we expect the RP to include in the submissions relevant to the environment case
• the proposed schedule for submitting information during Step 2 and Step 3

Our Step 2 review concluded that there were no identified fundamental environmental protection shortfalls in the design and that no significant issues have been identified so far that may prevent us from being able to issue a SoDA at the end of Step 3. The RP completed the submissions needed for Step 2 and is on track to make the necessary submissions for Step 3.

Overall there were no aspects of the design that were identified to be unacceptable and we have been able to make the following judgements following our fundamental assessment:

• We are satisfied the RP has demonstrated that its design at this stage is likely to be consistent with the application of the best available techniques for minimising the impact of radioactive waste disposals on people and the environment.
• The RP has made significant progress in considering sustainability when developing its organisation and design.
• We agree the radiation dose to people and non-human biota from radioactive waste discharges and disposals is likely to be below relevant dose limits and dose constraints during normal operations.
• An independent review by Nuclear Waste Services of the future disposal of spent fuel and certain solid radioactive waste streams has concluded that they are likely to be able to be disposed of in a future geological facility. We agree with this view.
• We agree that the RP is applying relevant legislation, regulatory requirements and relevant good practice in its design decisions.

We have concluded that we can progress to Step 3 of GDA (detailed assessment). Our Step 2 Fundamental Assessment Report provides more detail.

ONR has also concluded that it can progress to Step 3 (detailed assessment) of GDA and its Step 2 report is available on the ONR website.

6. Permissions and consents for a nuclear power station

Any company that wants to build and operate a new nuclear power station must obtain several site-specific permissions. These include:

• environmental permits from the Environment Agency or Natural Resources Wales
• a nuclear site licence and relevant consents from ONR
• planning permissions from the Planning Inspectorate

Rolls-Royce SMR Limited, supported by the Nuclear Decommissioning Authority (NDA), had previously completed a siting assessment review into the potential options for using the Rolls-Royce SMR. No further information has been received relating to this review.

The company has been selected as a nuclear technology provider for the Solway Community Power Company Limited that has set out an ambition to bring new nuclear power to West Cumbria.

The Rolls-Royce SMR has been shortlisted by Great British Nuclear for its Small Modular Reactor competition. The 6 designs shortlisted are considered most able to provide nuclear energy to the grid by the mid-2030s. Should the Rolls-Royce SMR design be selected by Great British Nuclear, a development site will be allocated. The Oldbury-on-Severn and Wylfa sites have been acquired by Great British Nuclear but no decisions have been taken to match designs to sites. The government also recently stated that Wylfa is its preferred site for a large, gigawatt scale nuclear power station.

Currently, no developers have applied for an environmental permit to use the Rolls-Royce SMR in the UK.

6.1 Nuclear site licence

ONR regulates the nuclear safety, conventional health and safety, security and safeguards at nuclear sites. Any organisation that wants to carry out nuclear activities must apply to ONR for, and be granted, a nuclear site licence. It must do this before it starts building a new nuclear power station. Granting a nuclear site licence is a significant step, but, on its own, it does not give an organisation permission to start nuclear-related construction. For that, it must get a regulatory permission from ONR.

6.2 Planning permission

A developer using the Rolls-Royce SMR needs a Development Consent Order from the Secretary of State for the Department for Energy Security and Net Zero. The Secretary of State makes a decision having received a recommendation from the Planning Inspectorate.

The environment agencies are consultees in this process and provide advice throughout.

6.3 Electricity generation licence

An operator would need an electricity generation licence from Ofgem, the regulator for the gas and electricity markets.

6.4 Other permissions

The operator will also need agreement from government about a Funded Decommissioning Plan and Regulatory Justification for the use of a new reactor design.

Other requirements could include additional permits and licences from the Marine Management Organisation (England), Natural England, Natural Resources Wales, and local district and county councils.

7. Public and stakeholder engagement for this GDA

We have set up our GDA process to be open and transparent.

Public comments process

Rolls-Royce SMR Limited is encouraged to publish detailed design information on its website and to update it as new information becomes available. Anyone can view that information and comment on it.

Rolls-Royce SMR Limited is required to respond to questions and comments about its design. We see the questions and the responses, so that we can consider them in our assessments. Comments can also be made to the nuclear regulators’ Joint Programme Office.

Rolls-Royce SMR Limited’s GDA website and comments process was launched at the start of Step 2 (fundamental assessment) on 3 April 2023, so that the public can view and comment on the information the company is submitting for GDA.

There is also information about GDA and the comments process on the:

• joint regulators’ webpage
• Environment Agency webpage on assessing reactor designs for new nuclear power stations
• ONR webpage on new reactors
• Natural Resources Wales webpage on how they regulate the nuclear industry

During Step 2, Rolls-Royce SMR Limited published the information it is submitting for GDA (apart from any sensitive nuclear or commercially confidential information) on its website, allowing people to make comments through the website or by post.

Rolls-Royce SMR Limited also promoted the publication of this information, the comments process and the new website. Information was included in press releases, on its social media channels and shared at public events, conferences and industry events that it attended.

The nuclear regulators also publicised the second step of GDA and the comments process through the media and directly to stakeholders.

Thirty-six comments were received during Step 2. They were mainly supportive of the RP and the design, with specific topics including:

• looking at the opportunity to use the heat of the reactor for beneficial purposes such as district heating or industrial processes
• support for building British engineering skills and jobs
• support for a smaller physical footprint when compared with a gigawatt power station
• questions about the regulatory and planning processes and public participation
• local environmental impacts from construction

The regulators have considered comments they received up to 30 April 2024, and Rolls-Royce SMR Limited’s responses to those comments, during our Step 2 assessments.

None of the comments directly affected our assessment or our GDA process.

We will consider comments we receive after 30 April 2024 during the next stage of our assessment.

Public consultation

While it will always be the regulators’ responsibility to make decisions about the assessment of nuclear power station designs, we want our decisions to be better informed through good engagement.

It’s important to us that we involve people in decisions that affect their community. We want to understand peoples’ comments and views. Where relevant we can use these to help inform our assessments.

Towards the end of 2025, we’ll publish a consultation plan. In January 2026, we’ll publish a document that sets out our preliminary conclusions on the design alongside our assessment reports. We’ll launch a 12-week public consultation on these conclusions.

We will not make our final decisions on the Rolls-Royce SMR until we have carefully considered comments from the consultation.

Get involved

You can get involved in our GDA by:

• reviewing the information and commenting through Rolls-Royce SMR Limited’s website
• taking part in our consultation – we will consult on our preliminary findings from Step 3 (detailed assessment) and consider all the relevant comments received, using them to inform our assessments and decisions about this design
• talking to us at public, stakeholder and industry events

The regulators have published an approach to engagement for this GDA on their joint webpages.

If you have any comments on the plan, please email nuclear@environment-agency.gov.uk.

8. GDA timetable and next steps

The GDA of the Rolls-Royce SMR is currently planned to last 4 years and 9 months.

• Step 1 (initiation) started in April 2022 and finished in March 2023
• Step 2 (fundamental assessment) started in April 2023 and finished in July 2024
• Step 3 (detailed assessment) is planned to start in August 2024 and finish in December 2026

A public consultation on our preliminary findings of the assessment will start during Step 3. This is planned to start in January 2026.

Following the consultation, we will carefully consider all responses before deciding whether to issue a SoDA, iSoDA or neither.

We plan to publish our decision towards the end of 2026, which will be the end of the GDA process for the Rolls-Royce SMR.

9. Contact us

You can feed back on this document or our work on assessing this design.

Environment Agency

Call us on 03708 506 506 (Monday to Friday, 8am to 6pm)

Email: nuclear@environment-agency.gov.uk

Natural Resources Wales

Call us on 0300 065 3000 (Monday to Friday, 9am to 5pm)

Email: enquiries@naturalresourcewales.gov.uk

By post:

Natural Resources Wales
c/o Customer Care Centre
Ty Cambria
29 Newport Road
Cardiff
CF24 0TP